Postal system

ABSTRACT

A machine for sorting and gathering together articles of like distribution, such as letter mail, which is randomly positioned in a supply source. Each article, being in a respective one of a plurality of categories, is initially sorted by destination or alternatively reclassified to be sorted by dispatch as the machine approaches capacity, so as to provide continuous sorting. Storage means for tallying inventories, and code generating means are included, as well as dynamic program control and physical means for supply source enrichment, tying, and labeling.

United States Patent William M. l-lolme Falls Church, Va.

Feb. 24, 1969 Apr. 6, 1971 International Business Machines CorporationArmonlt, N.Y.

Inventor Appl. No. Filed Patented Assignee POSTAL SYSTEM 3 Claims, 5Drawing Figs.

U.S.Cl. 340/1725, 2l4/llR lnt.Cl. G061 15/46 FieltlofSearch 340/1725;235/l57, l51.l,15l.1l;2l4/ll DEPOSITING MEANS j 34 [56] References CitedUNITED STATES PATENTS 3,300,066 1/1967 Henig et a1 214/11 3,312,9494/1967 l-lenig 340/1725 3,320,593 5/1967 l-ledrick et al. 340/17263,397,392 8/1968 Henig et al 340/ 1 72.5

Primary Examiner- Raulfe B. Zache Attorneys-Hanifin and Jancin andMelvyn D. Silver ABSTRACT: A machine for sorting and gathering togetherarticles of like distribution, such as letter mail, which is randomlypositioned in a supply source. Each article, being in a respective oneof a plurality of categories, is initially sorted by destination oralternatively reclassified to be sorted by dispatch as the machineapproaches capacity, so as to provide continuous sorting. Storage meansfor tallying inventories, and code generating means are included, aswell as dynamic program control and physical means for supply sourceenrichment, tying, and labeling.

r COMPUTER TYING mama] m man 3573; 74s

, PRIOR ART u DEPOSITING MEANS WILLIAM M POLHE 4 BY/%Db% AGENT POSTALSYSTEM FIELD OF THE INVENTION Means to convey a number of articles ormasses of material and deliver a predetermined article or mass to apredetermined point, as a delivery station, according to the will of theoperator, there being a plurality of stations, and whereby any articlemay be delivered to any station at the will of the operator under hiscontrol at a control station.

BACKGROUND OF THE INVENTION Sorting systems become increasingly complexas the random mix and number of articles to be sorted increases, as wellas the variety of destinations or categories into which these articlesare to be sorted, and the distribution network complexity for handlingis increased To illustrate, mail deposited at a local post office may bein package or letter form. It is initially deposited into a postal boxcontaining similar packages or letters randomly positioned in that box,where each of those articles may ultimately go to any one of some 33,000post office locations in the United States prior to ultimate delivery tothe addressed recipient.

Any sorting system to handle such a wide distribution of articles to besorted must have a capability of being able to sort individual pieces toform larger handling units going to any individual location, whilesimultaneously performing this function in a manner so that overloadingor jamming of the accumulation unit will not occur. While it istheoretically possible to have a destination slot, bin, or receptaclefor each conceivable destination or for each of the 33,000 post offices,into which every article destined for that destination may be deposited,irrespective of size or shape, as a practical matter the incidence orprobability of an article deposited at any one location being addressedto certain destinations may be extremely low. This being so, theeconomics of the system dictate that fewer sorting slots than themaximum number of destinations possible be provided in the physicalconfiguration of the sorting machine, while still maintaining a capacityfor separating to every destination articles thereto addressed. Thus, itis an object of this invention to utilize a computercontrolled machinesystem for separating, identifying and classifying, sorting, gathering,and rerouting of articles, par ticularly mail, in an integratedman-machine computercontrolled processing system.

A further purpose of this invention is to process any type of material,not necessarily mail, wherein the number of possible distributions in asorting function is very large relative to the number of sortingseparations which may be individually active (or which may receive aplurality of items during a processing period), and which is subject toinput media containing unpredictable and/or varying distribution ofcontents to be sorted, rearranged, and distributed.

Another more specific object of this invention is to provide a systemfor processing of flat mail, small parcels and rolls, parcels and junkmail, destined for any one of a number of post office locations.

SUMMARY These and other objects are met by this invention. Briefly, inone embodiment, this invention comprises a data storage and processingmeans; a primary temporary holding sort means comprising a plurality ofpresort buffer temporary storage slots; means for generating an addresscode representing the destination category of each of the articles to besorted, the address code being stored in the data storage means;depositing means for depositing each article in a selected temporarystorage slot, arbitrarily and dynamically selected on the basis ofimmediate availability, and identifying the contents of that slot by thearticles destination category; means for discharging from the temporarystorage slots the articles contained therein; and means for keeping arunning inventory of articles in each address code held in temporarystorage slots and a running count of the extent to which each of theplurality of sorting slots is occupied, the total number of sortingslots occupied, including the destination category of objects, held ineach of those slots, a running inventory and the running count beingstored in the data storage means; and means for generating a destinationsort code capable of actuating the discharge means to discharge from theplurality of sorting slots all articles of a given destination category,in dependency upon the running inventory and running count, thedestination sort code being operative when less than an arbitrarilydesignated number of the plurality of sorting slots is occupied; andmeans for generating an alternate dispatch or sort code also capable ofactivating the discharge means to discharge from the plu rality ofsorting slots articles of different categories, in dependency upon therunning inventory and the running count, the dispatch sort code beingoperative when more than an arbitrarily designated number of theplurality of the temporary storage slots is occupied; and a programcontrol and switching means for switching operation between thedestination sort code and the dispatch sort code in dependency upon thearbitrarily designated number of the plurality of sorting slots beingfilled. In this manner, the sorting machine is continually alternatingbetween destination sorting and dispatch sorting as a function of thenumber of slots occupied at any given time and the amount of mail forvarying destinations located within those slots. Further, enrichmentmeans for continually enriching and thus affecting the randomness of themail in the supply source is also provided.

The invention may best be understood in conjunction with the followingdrawings and general description.

IN THE DRAWINGS FIG. I is a schematic representation of part of thesorting system of a prior art system. FIG. 1A is an alternate embodimentofthe system of FIG. 1.

FIG. 2 is a schematic representation of part of a prior art sortingsystem, from single letter input to multiletter sorted output.

FIG. 3 is a schematic representation of the sorting system of thisinvention from single letter to bundled, tied output of stacks of sortedmail.

FIG. 4 represents one embodiment of a conveyor belt assembly for usewithin the sorting system of FIG. 3.

GENERAL DESCRIPTION Before describing the system of this invention, itis necessary to thoroughly understand prior art sorting systems thathave attempted to solve the above problems. One of these is known as the"extended reach" or conveyorized method ofsorting.

Referring to FIG. 1, this sorting machine essentially consists of aconveyor 1, separated into a series of compartments 1; a fixed proximatenumber of receptacles 7, and a number of mechanisms 4 along the conveyorlength, associated with each receptacle 2, the mechanisms incorporatinga plunger, arm, or other mechanical device 15, capable of pushing orotherwise rejecting mail 6, or other items, into fixed, adjacent accumu-Iating receptacles 7 so as to form a stack 8 therein. The essentialfeature of this system is that it transports items, such as the mail 6,to a preestablished fixed distribution point, where it mechanicallyejects and/or releases items into an accumulation receptacle 7 forremoval and further routing. The memory and control system to operatesuch a system is described in concurrence with a later prior art systemdiscussed, the "sweep sort" system.

A widely used alternate of the extended reach system is il- Iustrated inFIG. IA, wherein the conveyor consists essentially of a number ofreceptacle boxes 9, each compartment 10 of which is capable of holdingone unit II to be sorted.

The bottom of each compartment is designed with a trap door 12 such thatits contents may be released, by command of appropriate control devices,to an appropriate proximate fixed accumulating receptacle 14 for furtherdisposition.

This method is sometimes referred to as extended reach sorting, since itmechanically makes it possible to make more separations then aremanually feasible within the physical limitations of human arrn reach.

Modified extended reach systems are systems which accomplish moreseparations then are possible in one pass through the machine, by makinga primary separation to major categories on the first sort, then,clearing all accumulation receptacles, and resorting within onepresorted group, through the same or an equivalent machine to asecondary classification. Thus, for instance, up to 10,000 separationsmay be made by two sorting separations through a IOU-pocket separationmachine, employing some means of identifying the material to be sorted,so that it may be automatically processed in the second, or any othersubsequent operation.

In one concept variation, material to be sorted may be identified in thefirst separation by machine imprinting, labeling, or machine readableencoding at an induction station, so that it may be machine read andprocessed in the subsequent processing. In another variation of thisconcept, the material to be sorted may be containerized, itemidentification for sorting purposes encoded upon such containers,containers sorted through the first machine, and then distributed to asecond similar machine for further mechanical sorting. Thetransportation from first to second machine may be in trays, blocks, orgroups of items, or it may be done on a subsidiary conveyor system forcontinuous flow from output receptacle of the first machine to the inputstation of the second. In either case, this modified system utilizes thesame original extended reach type of machine concept as above (fixedoutput pockets, moving distributing conveyor), adding to it a method ofidentifying the material sorted so that it may be subsequentlyreprocessed for further distribution, without additional manual handlingof individual originating units.

SWEEP SORT SYSTEM The prior art sweep sort system offers severaltheoretical advantages over the extended reach system. Referring to FIG.2, the system consists essentially of individual induction stations 2],an online computer control system 22, holding receptacles 23, and aconveyor system 26. The holding receptacles 23 are fixed in positionover or otherwise proximate to the conveyor 26, and are divided intoindividual separate compartments 24, each of which incorporates atrapdoor 25, capable of being quickly and remotely opened upon commandfrom computer 22 to a discharge activating means, not shown. Theconveyor system 26 is discretely zoned longitudinally along its system,so that each designated section 27 may accumulate material, as indicatedat 28. The position of each section 27 on the conveyor, relative to thefixed receptacle 24 along the system, is known at all times by acomputer register system which dynamically advances the position of theconveyor belt in its register, as it moves. The clock in the computerwhich controls this advancement is in turn set synchronized to theconveyor itself, by suitable, electronic, mechanical, or photoelectricpulse triggering devices, well known in the art.

In operation, an operator at induction station 2] reads the address of apiece of mail 21a presented, and keys at memorized sort disposition codefor this address into the keyboard 29. This information is transmittedto the computer system 22 via a direct wire or radio link. The computer22 refers to its memory to determine which compartment of the holdingreceptacle 23 is unoccupied, assigns the sort disposition code of theitem being sorted to its data storage record for that individualreceptacle, and issues a command to a mechanical transport system (notshown) to deposit the mail into that particular receptacle.

In this way, mail is classified, presorted and moved into open availablefixed receptacles, under control of the computer which determines thisrouting, and retains in memory the desired ultimate disposition of everyunit to be sorted. This function is repeated for any desired number ofinduction stations along the length of the conveyor 26, as required byrate and volume requirements of the system.

Concurrently, the computer accumulates and reviews, in a separateassigned memory storage within the computer, the number of pieces ofmail for each different sort category deposited in the storagereceptacles, throughout the entire system, as well as their locations.Whenever enough pieces of mail have accumulated throughout the system tomake a bundle large enough to tie, the computer dynamically assigns amoving belt section 27 to that destination and commences a routine whichcompares the address of that belt section with the address of mail ineach induction receptacle, as the conveyor belt moves under it.

The location of any such dynamically assigned conveyor section, movingalong the conveyor under the induction storage receptacles 24 is knownrelative to the individual holding receptacles 24, on a real time basis,by the computer system, which advances conveyor section 27 assignmentsthrough its registers in synchronization with the physical movement ofthe conveyor 26. The computer clock is controlled by signals from theconveyor as it moves.

As an assigned section 27 on the conveyor 26 moves under an inductionstorage receptacle compartment 24, which holds a piece of mail forsection 27s now-assigned destination, the computer transmits a controlsignal to a solenoid mechanism, for example, which releases trapdoor 25for that compartment. This permits the contents of that compartment 24to fall down into the advancing conveyor section 27. As conveyor 26advances under all of the induction storage units, it thus accumulatesand groups mail for specific destinations on its separately assignedbelt sections for discharge and disposition in sorted categories at theend of the conveyor system.

Concurrently, as the induction holding receptacles 24 release theircontents, the computer clears its storage of any assignment of mail tothe same, closes and resets the trapdoor, and thereby makes thatreceptacle available for assignment to, and use by, another piece ofmail.

A feature of this system is that any given induction station receptacle24 may be assigned to and used by only one piece of mail at a time;conveyorized sections 27 are assigned to only one destination at a time,but hold multiple pieces of mail. The assignments of destinationaddresses to both induction receptacles 24 and conveyor sections 27, aredynamic, being reassigned on a real time, online basis by the computersystem. The input compartments are fixed, the output belt sections aremoving.

This is exactly opposite to the extended reach sorter system, whereinthe input receptacles are conveyorized and moving; and outputcompartments are fixed, both physically and as to destination ofcontents.

The purpose of this sweep sort system is to provide a means of handlinga larger number of output distributions than is possible with a fixedpocket extended reach type of sorter, and to pennit complete processingand distribution of the mail without multiple handlings.

Each of the three general systems outlined above contains intrinsicshortcomings, for processing and distribution of mail.

A. The extended reach type of sorter is practically limited in number ofseparations it can make, economically and physically.

l. Beyond a certain number of separations, the utilization of pocketsfor less active destinations becomes so light, that it is not economicalto make machine provision for such sorts.

. Physical size also becomes a limitation where too many separations areattempted, relative to the throughput capability of the machine.

. Because of limitation I, this type of sorting requires multiplehandlings in order to obtain the required number of separations. Forexample, current post offree machines accomplish from -300 separationsin each pass; whereas 34,000 distinct post office tieout separations(out of a total of 33,000 different post offices) is not uncommon for amajor postal processing center.

4. No provision is made for clearing the output of the machine from itssorting pockets. The system thus requires manual support at the outputend, and processing is not fully mechanized.

5. Because of the uneven and extreme activity volumes of different postoffices, the fixed output pocket type of sorter tends to fill up itspockets for very active destinations extremely fast. This createsjamming, and/or severe problems in clearing the machine; or requiresmanpower in excess of the work content that orderly removal wouldotherwise indicate.

B. The modified extended reach systems attempt to overcome theshortcomings of A, by using smaller (less separation) machines, adding ameans of encoding the mail (or a unit mail container) for subsequenthandling. By using machines with less separations, the machineutilization per pocket is more efficient, which permits mechanizedsweeping and removal means. By employing a system for encoding andmachine reading of the mail, for subsequent handlings, the added cost ofmanually reading and keying the mail for subsequent handlings, after thefirst, may be largely mechanized, at optimum machine rates, reducing thedisadvantages of multiple handlings, as appear in the basic extendedreach systems.

Nevertheless, these configurations still retain, in reduced degree, thebasic disadvantages of any extended reach system. The basicdisadvantages are as follows:

I. The system essentially addresses the input and sorting problem, butnot the one of disposing of the mail after it has been sorted.

. The reduced cost of lesser pocket machines is offset by added cost ofsweeping mechanisms to clear and stack machine output, where high-speedautomatic machines are desired. The cost of such machines appears toincrease in throughput rate.

3. It does require multiple handlings. As contrasted to manual sorting,which requires 3+ handlings per piece on outgoing separation, thissystem requires almost as many average handlings per piece (machine ormanual).

4. ln addition to the added machine cost, this system necessarilyrequires a costly system to either imprint and machine read the mail, orhandle and process special containers.

C. Computer simulation studies of the sweep sorting type of system haveshown this system not to be feasible, as was proposed. Specifically,those studies indicated that because there are many very low volume maildestinations, the input holding receptacle units tended to fill up allstorage receptacles, faster than accumulation and release of mail forspecific destinations would clear the machine. That is, in a multipleoperator input system, the number of pieces for a given low volumedestination, as processed into the entire system by a number ofdifferent operators within any short given period of time, do not buildup fast enough for the system to release them, before all holdingreceptacle compartments are filled up at some input stations.

Conversely, on the very high activity level destinations, a

number of input receptacle compartments for a few of the very highestvolume destinations tend to fill up faster than they are emptied, eventhough the dynamic sweeping system constantly reassigns conveyorsweeping to those destinations.

Thus, it was found that a ZO-compartment input receptacle system tendedto jam itself out of operation in 20-30 minutes; 50-compartmentreceptacle systems in an hour to an hour and a half; etc. The analysisultimately concluded that the number of input holding compartmentsnecessary to insure unjammed, continuous operation of the system waseconomically unfeasible.

THE INVENTION The machine of this invention is designed to address thefollowing situation. Quantities of mail on a continuing basis aredelivered to a local post office from various pickup stations. This mailis introduced into a series of bins from which it will be introducedinto the machine to be described. Bundled mail leaves any particularpost office only at certain times and along certain routes, inherent inthe function of that post office. For example, a post office may shipmail by truck l0 times daily to ID separate locations along 10 separateroutes; it may ship mail by air four times daily along four separateroutes; it may ship mail by train l2 times daily along four differentroutes.

It is desired that mail be sorted in such a manner that whatever mailhas been sorted to a given point at a given time be removed from therest of the mail being sorted or yet to be sorted so that it may beshipped via the train, air, or motor route on schedule. Thus, the mailmust be kept in motion and moving toward its ultimate destination withthe least amount of delay within the post office. The route that theair, motor, or rail carrier will take is the dispatch along which itruns. Those locations or destinations along which the carrier will stopor may discharge mail are destinations along the dispatch. It is alwaysdesired to keep the mail moving whether it be to a destination or alonga dispatch so that it may ultimately reach a destination in the leastamount of time. While these terms will be described in greater detaillater in conjunction with the operation of the machine, it should bekept in mind that this machine is designed as a real time system. Thecomputer, which is a basic part of the machine to be described, will becontinually checking a real time clock against the departure schedulesof the motor, air, or rail carrier, as well as the particular route ofthe carrier against the articles being processed through the machine atany one time.

Present mail sorting, which lacks the computerized mechanization, asdisclosed herein, separates mail on a geographical or numerical basis.That is, mail which is not sorted direct to a post office destination,is sorted to a secondary scheme," which could be a state, for instance.The invention disclosed herein is capable of either geographical ordispatch sorting for secondary separation.

This system is hermaphroditic: it combines basic unlike elements of theextended reach and sweep sorting type of systems, in one unitizedcontinuous flow unit, so as to overcome the limitations and shortcomingsof either of the other systems, including the modified extended reachmethod.

Essentially, the system consists of static input modules, similar to thefixed receptacle compartments of the sweep sorting system, with theexception that these compartments are so designed that they may hold asmall number of pieces of mail-up to 10 for exampleinstead ofjust onepiece only.

The output conveyor is segmented for gathering of discrete categories ofmail along its length, as in the previous sweep sort machine, but withthe additional feature that the belt is compartmented so that mail maybe retained on the conveyor, at the end of the belt, carried over,around, down, and back under the conveyor on its return pass, and thenreleased and be directly sorted to fixed position accumulation pocketsundemeath.

The machine consists of a plurality of operator input stations,configured so as to collect, collate. and gather together items having alike distribution from discrete temporary storage slots at the same ordifferent input stations into a common category bundle, and transportthem out of the system for disposition. FiG. 3 illustrates this machine,having, for clarity, but a single input station illustrated. An operatorreads mail 32 at station 31, presented by a machine system not shown,but well known in the art.

Each station, such as 31, comprises a first generating means forgenerating an address code representing the destination category of eacharticle, here a piece of mail. An address code may be, for example, thezip code representing the post office destination for that item; or itmay be an alpha-numeric code obtained by extraction from the fulladdress. Of course, in lieu of the letter, for example, being read by anoperator, it may also be read by a magnetic or optical sensing means ifeach letter has been previously magnetically or optically coded, or byan optical character reader or other such nonmanual reading means.

Thus in the system shown, an operator at a station, such as 3], readsthe address of the letter and by depressing appropriate keys on theconsole of the unit before him, converts the address to an address code.

The address code, once keyed, is transmitted to computer 56. Computer 56comprises a data storage means, capable of storing each address codealong with the address code for each post olfice. The computer memoryincludes, as a directory table, information as to other major processingcenters through which a destination post office may be furtherprocessed, and the dispatches on which it may be routed.

As in the sweep sort machine, an unassigned open slot 34 in primarytemporary holding sort means 33 is assigned to each address code,primary temporary holding sort means 33 comprising a plurality ofsorting slots 34. The mail is directed and moved into that sorting slot34 upon command by the computer 56 to a depositing means 60 fordepositing each letter according to the letter's address code in arespective one of the slots 34 located at an arbitrarily selectedlocation. The ad dress code identification of the sorting slot isretained in computer memory with the exception that if the address codeof that sorting slot has not already been filled with mail beyond itslimited capacity, the next envelope having that address code will bemoved into that sorting slot, rather than into a new one.

The computer, however, does have means for keeping a first runninginventory of each address code and a first running count of the extentto which the plurality of sorting slots is occupied, this first runningcount and first running inventory being stored in the storage means ofthe computer. Thus, at any given moment, the computer knows" the addresscode assigned to each sorting slot, the number ofletters in each slot,and the number of slots occupied, or conversely, those available to befilled, and their locations, and the total amount of mail in the entiresystem for each address code.

Similar to the sweep sorter concept, moving compartments 37 on conveyor36 are dynamically assigned to specific destinations by the computerfrom its inventory of mail in the sorting slots, and its releaseprogram, discussed later.

As the moving compartments 37 move under fixed sorting slots 34 in thedifi'erent input stations, having a corresponding address code, theaddress code match in the computer program causes solenoids, forexample, to be actuated so that the appropriate trapdoors 35 are opened,and mail is accumulated in stacks 38 for transport out of the system.

The solenoid-trapdoor combination would comprise, as an example, a firstdischarge means for discharging from the sorting slots the letterscontained therein. Other release means are, of course, available.

To this point, to discharge letters from these sorting slots into theconveyor compartments is required a second ge nerating means, in thecomputer, for generating a destination sort code, the destination sortcode capable of activating the first discharge means to discharge fromthe plurality of sorting slots all letters of a given address independency upon the first running inventory and the first running count,the destination sort code being operative when less than an arbitrarilydesignated number of the plurality of sorting slots is occupied.

Thus, up to this point, the machine operation may be described insummary.

Mail is automatically brought to an initial reading station. An operatorat this station reads the address on the mail. The operator depresses onthe keyboard before him the address code representing the post officedestination of that piece of mail prior to actual delivery by a mailmanto home or olfice. While zip code is one means of keying this mail,other means will known in the art are equally applicable. For thepurposes of this illustration, however, the operator will key the zipcode for that piece of mail. By his action, the operator has now giventhis piece of mail, which is in a given destination category, i.e., maildestined for a given post ofiice, an address code.

This address code is transmitted to a computer. The computer has storagemeans for retaining in its memory that that address code has beentransmitted to it, and will record the same in its inventory record. Thecomputer, in turn, instructs a depositing means to take that piece ofmail and deposit it into one of a plurality of sorting slots in theprimary temporary holding sort means.

Each slot may hold an arbitrarily designated number of letters, forexample, 10 letters per slot. Each piece of mail having the same addresscode is deposited in the same slot until such slot is full. At thattime, additional pieces of mail having the same address code aredeposited in the next available slot. The computer keeps track of thenumber of pieces of mail of each address code in each slot, the locationof those slots, and the number of slots filled or conversely, the numberof slots yet to be filled and thus available for additional categorycode sorting.

Each sorting slot has a first discharge means that can be activated uponcommand from the computer to discharge, for example, by gravity, themail contained in the sorting slot. in this illustration, a conveyorbelt having compartments upon it is operative and running beneath theprimary sort means. A second generating means, such as a computerprogram, is operative to generate a destination sort code within thecomputer. The destination sort code is capable of activating the firstdischarge means to discharge from the slots those letters for a givendestination category in dependency upon the running inventory and therunning count. The address code is operative when less than a givennumber of primary sorting slots are occupied.

The destination sort code will operate in the following manner, forexample. Assume that it is desired that each bundle of mail or each sortfor a given destination category contain no less than a given number ofletters, for example, 50 letters. If each sorting slot can hold 10letters, this would require that no discharge take place from thesesorting slots until five of such slots or the equivalent, were fullthroughout the system. Thus the computer, keeping track of the locationof each category code within a slot and the number of slots occu pied,would at a given point (50 letters in the sorting slots) clear thoseslots having the same address code of the mail contained therein. Thisis done by choosing an empty compartment on the moving conveyor and asthat compartment passes beneath the sorting slots, serially triggeringthe sorting slot release means upon command from the destination sortcode, thus releasing the mail of a given address code into that chosencompartment on the conveyor. Thus in the illustration given, a number ofdifferent slots at different locations would serially discharge mail ofthe same given address code into the same conveyor compartment as thecompartment moves beneath the slots.

The empty slots are now available, of course, for mail of other addresscodes. Thus, upon command from the computer via the destination sortcode, the primary temporary holding sorting means is continually emptiedas mail is sorted, and continually refilled by the depositing means viathe initial system described. Thus, a real time dynamic system is inoperation.

The sorted mail in the conveyor compartments is conveyed directly intoand through an online automatic tying machine 42 which ties and labelsthe mail under computer control. The conveyor unit performs two otherfunctions as will be described subsequently.

Not all mail is processed in this fashion.

As mail temporarily accumulates in the sorting slots 34, and the numberof available unused sorting slots approaches a critical minimum number,the computer will determine, by preset programmed rules, whether or notto release less active address destinations or address codes, by makingsmaller bundles for tie-out, or to activate an alternate routine. ln anyevent, when an arbitrarily designated number of the plurality of sortingslots is occupied, an alternate routine takes over.

Initially, the computer program has a constant number which is thenumber of pieces of mail desired to be accumulated for a destination,before mail for that destination is to be released, swept, and tied outinto a bundle.

A second program polls the contents of the different temporary storageholding receptacle stations. Whenever the contents of any stationapproach saturation, such that it will shortly be unable to receive moremail, the program initiates a modification routine on the number ofpieces of mail required to make a tie-out, reducing the same in fixedincrements, down to 10 letters per bundle, for example, until theimpending bottleneck is released.

As soon as the impending saturation relieved, the program reverts to theoriginal constant number of pieces for a bundle. If the program iteratesand advances down to lO-letter bundles, without correcting thesituation, the alternative routine is called out.

Assuming that the latter has become necessary to clear the system, thecomputer then searches its stored inventory balance infonnation for theaddresses for all pieces of mail in storage for which there is only onepiece of mail in the temporary storage holding compartments. For each ofthese, the address is looked up against a table, to determine the nextdispatch on which each of those pieces of mail is going out (or to whichpostal processing center the mail should be sent for further separation,in an alternative system). Stored data, as to address disposition ofthose pieces of mail, in their respective individual temporary storageholding compartments, is then updated in memory, to correspond to thenew disposition address, based upon a dispatch or secondary sort schemecategory.

Qnly those pieces of mail which have an address inventory balance of oneare initially so recategorized in the first iteration, and processed asdescribed below.

The disposition is determined by a dispatch sort code. This requires athird generating means, in the computer, for generating a dispatch sortcode, the dispatch sort code also capable, as with the destination sortcode, of activating the first discharge means to discharge from theplurality of sorting slots articles of different destination categories,in dependency on the first running inventory and the first runningcount, the dispatch sort code being operative when more than thearbitrarily designated number of the plurality of sorting slots isoccupied. Thus, an initial and primary difference is that whereas thedestination sort code will cause release of all articles of a givendestination category, the dispatch sort code discharges articles ofdifferent destination categories but the same dispatch category from thesorting slots. The dispatch is sorted in the following manner.

Where there are an insufficient number of articles to form a tie-out orbundle for a given destination, and the machine temporary holdingsorting slots become overly occupied, i.e., tendency toward fullutilization and thus jamming, the dispatch sort code will cause releaseinto a single moving compartment on the conveyor of the contents ofthose sorting slots having addresses which contain the least number ofarticles therein, with a common factor being that while address codes ofeach set of articles from each sorting slot is different for eachrelease to a compartment on the sweeping conveyor, all will ultimatelybe delivered to their destinations along the same route or dispatch. Forexample, if a railroad train were to deliver mail from New York City toPoughkeepsie, N.Y., passing along its route Yonkers, Dobbs Ferry,Hastings, Tarrytown, Ossining, Peekskill, Cold Spring, Beacon, andfinally terminating at Poughkeepsie, mail destined for any of those locations to go onto that given train would constitute the dispatch forsuch mail. Thus, many destinations lie along a given dispatch. Thedispatch sort code would thus cause clear ing of the least filled slotslying along this dispatch. In contradistinction, a destination sort coderelease would release only mail going to one of those given locations,i.e., Tarrytown or Ossining, etc.

The code then updates and sets the computer registers for those sortingslots by a mail processing dispatch number, instead of destinationaddress, and dynamically assigns conveyorized compartments 37 to suchdispatch number codes, so that mail will now be accumulated in groupsalong the conveyor by dispatch, rather than by destination address.

The system is so programmed that when it becomes necessary to reassigndisposition codes (i.e., from destinations to dispatches), only thosepieces of mail having one piece of mail per address, throughout thesystem, are recoded, released, and swept into dispatch compartments. Thecomputer then reevaluates the storage condition of the temporary storageholding slots. If the approaching saturation condition, which previouslycaused the reassignment routine to begin has been relieved, the systemgoes back to releasing, sweeping, and gathering mail for direct addressdestinations only as it had been, previously. If the impendingsaturation condition is not relieved by releasing pieces of mail forwhich there is only one piece of mail per destination, the reassignmentroutine reiterates and searches inventory for all those pieces of mailfor which there are only two pieces per destination, reassigns theiraddress category to dispatch (or some other secondary scheme), andreleases for gathering and sweeping in the conveyor compartments, asbefore. This routine reiterates one additional piece of mail perdestination count for reclassification, up to 10 pieces of mail for anaddress, if necessary, until the approaching saturation utilization ofthe temporary holding slots condition has been relieved. No more suchreclassification of address categories is made than necessary to relievethe filling up of temporary holding slots beyond unsaturated workingcapacity; the object of this routine being to prevent temporary storageslot saturation, by removing the minimum amount of mail necessary.

Thus, when the number of sorting slots occupied becomes less than thearbitrarily designated number, a first program control and switchingmeans in the computer, switches operation from the dispatch sort codeback to the destination sort code for continued operation.

As the compartments 37 which hold reclassified mail for dispatch orsecondary separation go through the tying, labeling, and bundle sorterunit 42, the computer program activates an alternative instruction tothe unit 42 which causes it to bypass the tying operation, and allowsthe compartment to pass around, under, and back along the underside ofthe conveyor.

As such batches of mail return along the underside of the conveyor, theyare held onto the conveyor, until they pass a collection station 40which has been assigned to a specific, fixed dispatch (or secondaryseparation grouping) by the dispatch sort code via computer command.

At that point in time, determined by the dynamic computer memory, whichis advancing data in synchronization with the conveyor and matching thesame with correspondingly adjacent collection stations, the computerprogram releases a command instruction which causes the mail so carriedto be dropped into its appropriate dispatch collection station, whichmay comprise a bin or tray.

Additional means are here present to keep a second running inventory ofeach address code within each dispatch, the number of articles collectedin each collection station, the dispatch code for each collectionstation and the location of each collection station. All this is storedin the computer data storage means.

The mail is accumulated in collection stations 40 until the time aparticular dispatch is to be processed or the number of articles in anygiven collection station exceeds a predetermined number. This is done asfollows.

The computer, keeping track of the number of articles in any givencollection station and the address codes therein, finds through arunning tally that that collection station contains enough mail along agiven dispatch of the same address code to allow a secondary sort byaddress code. Thus the computer will activate means for reintroducingmail collected in that collection station into the supply system Thismail then comprises enriched (i.e., a concentration of mail for alimited number of destinations) rather than random distribution of mailfor 33,000 different post offices as originally supplied. Additionaltie-outs may then be made, by further sorting, if the computer inventoryindicates that the distribution of mail within that group warrants thesame.

However, this being a real time system, there may be insufli cient mailwithin each destination category to warrant such a sort. As the timeschedule programmed within the computer signals that any mail to goalong the dispatch, as for example from New York City to Poughkeepsie,must be pouched for delivery to that train by a given hour, it may callout all mail along that dispatch to be reintroduced within the unit,sorted into separate sorting slots, and if these slots still containinsuf ficient amounts of mail to warrant a destination sort, the machinewill then reassign sorting instructions to call out a sort to anotherpostal processing center closer to the destination for such tie-out. Inthis manner, both mail to a specific end-point destination, and dispatch(or secondary scheme) coded mail can be bundled in sufficient time tomeet a carrying means such as the train cited, for prompt deliver. Ofcourse, as is well known in the post office, dispatch mail goes to asectional center post office where the volume of mail for destinationsalong the dispatch is greater than at the originating station, wherebythis mail is introduced into the original source from that post office,destination coded by another machine similar to that being heredescribed, for ultimate destination delivery. Thus, the mail from onedispatch is reintroduced into the system and reprocessed. Since thereare only a limited number of separations on any one dispatch, and thismail has been enriched to the extent that it has already been gatheredtogether into a limited number of destinations comprising a dispatch,all mail will be tied out into either a direct destination or a transitpost office destination for further processing. There is no further unithandling.

The tying and labeling machine 42 includes within its design thecapability of removing all bundles which have been tied and labeled,from the conveyor. This function may thus be performed mechanically, aswell as manually.

Tying and labeling instructions are, of course, received from thecomputer, synchronized with the arrival of the conveyor compartments ofthe mail to be tied and labeled. This unit, therefore, has thecapability of serving as an induction station to a connected bundlesorting machine, not shown.

At this station the mail is either bundled, removed, and sorted into asack, or the sweeping conveyor system carries it through, around, andunderneath the conveyor system so that it may be automaticallydischarged to fixed pocket collection stations underneath the machinefor a second handling.

Just as the sorting slots may become "overutilized" with a tendencytoward jamming, the same is true of the collection stations beneath theconveyor. Thus, additional means may be provided for allowing dischargefrom the collection stations of articles contained therein, and meansfor generating an enrichment code, the enrichment code capable ofactivating the discharge means to discharge from the plurality ofcollection stations all articles of a given dispatch, in dependency uponthe second running inventory and the number of collection stationsoccupied, the enrichment code being operative when an arbitrarilydesignated number of collection bins is occupied; and means forgenerating a station clear code, the station clear code capable ofactivating the second discharge means to discharge from the plurality ofcollection stations articles of different dispatches, the station clearcode being operative when more that an arbitrarily designated number ofcollection stations is occupied; and second switching means forswitching operation between the enrichment code and station clear codein dependency upon the arbitrarily designated number of collectionstations being occupied. Thus, the collection bin storage problem ishandled in the same manner as the sorting slots occupation problem ishandled in the primary sort means. In normal operation, of course,collection bins are continually being emptied to form enriched mail inthe supply source, so that ultimately most mail may leave via adestination code, i.e., by category code.

Many mechanism are possible for the compartmented conveyor which permitit to carry mail around its end, and back along underneath, so as to dodirect sorting on its return pass.

One possible means by which this might be accomplished is shown in FIG.4. Attached to conveyor 36 (cut away to show detail), the compartmentseparators SI may be constructed with a spring-loaded hinge 57, so thatnormally they stand straight out from the conveyor, as in position B,but when constrained by an interfering member, they will fold back toform pockets, as in positions A and C.

In FIG. 4, these pockets incorporate extensions $20 at either or bothsides, upon which small wheels or rollers 52 are mounted.

As the compartments pass around the output end of the conveyor at C,fixed rails 46, shown in FIG. 3, engage the extending rollers 52 on thetop or outer edge of each compartment to fold back around theirspring-loaded, hinged sections 57, in FIG. 4. Thus, any mail still inthe compartment is held in place by that portion of the compartmentwhich is folded back and becomes the trailing bottom of an enclosedpocket 44, in FIG. 3, and is shown holding a piece of mail at 49.

As these compartments are moved from right to left underneath theconveyor, that portion of the leading wall 51, HO. 4, which isarticulate, is held in a horizontal position, as a pocket, by the wheelsor rollers 52, as they engage and roll over segmented sections of tracks53, adjacent to the conveyor compartments. The segmented sections oftrack 53 are mounted in a hinged way at their forward ends 58, so thatthey can be externally actuated at ends 59 to pull them out and awayfrom the otherwise continuous, segmented track (sections 53),illustrated in position B,

Thus, when it is desired to release mail from the pockets, the computerwill actuate a solenoid, not shown, so as to pull the section of trackover the desired sort pocket out of engagement with its adjoiningsection of track at one end (B). When this occurs, there will be nosupport for the next compartment pocket moving into position; thespring-loaded compartment wall will spring down into a verticalposition, and contents of the pocket will be released. Compartments sorestored to their original upright position (now upside down), willretain this position throughout the remainder of the conveyor cycle,until reset into pockets by the fixed turn-around track unit 46, at theend of the conveyor, as shown in FIG 3, which functions as a cam toclose the pockets.

It will be seen that this system overcomes the obstacles which preventedthe original sweep sort letter sorting machine from being feasible, asfound under simulation, in many ways:

I. By permitting the accumulation of more than one piece of mail for onedestination in an induction receptacle compartment, it substantiallyreduces the loss of capacity that occurs when a very high volume run ofmail occurs for one destination at one input station.

2. By providing a means to remove, sort, and enrich very low densityoutgoing mail, using a direct sort feature in addition to the sweep sortconcept, the system can be controlled so that it will never fill up andstop. At the same time, it continues to make direct tie-outs of thelargest possible number of destinations at all times, optimizing thetie-out scheme on the basis of current mail distribution patterns.

3. The end result of this configuration is a system which will separateand sort the mail in only slightly more than one handling per unitpiece; in a larger post office, only l020 percent of the outgoing mailmay require a second handling. This represents a substantial improvementover any other known mail sorting systems manual or machine.

4. The portion of mail requiring a second handling is so small that thefunction of machine imprinting and coding may not be required.

5. The system is essentially "continuous flow," i.e. accomplishes theoriginal objectives the sweep sorter tried but failed to achieve, andrequires substantially less costly mechanical handling devices than thevarious existent or proposed extended reach machines.

While this system has been described primarily with mail sorting inmind, it is evident that by proper choice of slot sizes, etc., otherarticles besides mail may be sorted. And while particular means havebeen described, equivalents are possible, and likely as technologyimproves.

lclaim:

l A machine for sorting articles by collecting them from randomlypositioned locations from at least one of a plurality of supply sources,each article being in a respective one of a plurality of destinationcategories comprising:

first generating means station for generating an address coderepresenting the address of each of said articles;

a primary sort means comprising a plurality of temporary holding slots;

depositing means for depositing each article in selected respective oneof said slots;

first discharge means for discharging from said slots the articlescontained therein;

collecting means for collecting and labeling the articles discharged bysaid first discharge means;

tying means for selectively tying said articles collected by saidcollecting means;

collection stations for storage of those of said articles notselectively tied by said tying means;

a control computer, said control computer further comprisa means forkeeping a first running inventory of the number of articles in eachaddress code by slot location and a first running count of the extent towhich said plurality of sorting slots is occupied,

a second generating means for generating a destination sort code, saiddestination sort code capable of activat ing through said computer, saidfirst discharge means to discharge from said plurality of sorting slotsall articles of a given destination category, in response to said meansfor keeping a first running inventory and said first running count saiddestination sort code being generated when less than an arbitrarilydesignated number of said plurality of sorting slots is occupied,

third generating means for generating a dispatch sort code, saiddispatch sort code capable of activating through the computer said firstdischarge means to discharge from said plurality of sorting slotsarticles of different destination categories, in response to said meansfor keeping a first running inventory and first running count, saiddispatch sort code being generated when more than an arbitrarilydesignated number of said plurality of sorting slots is occupied, andfirst control and switching means responsive to said means for keeping afirst running count and said arbitrarily designated number of saidplurality of sorting slots filled at a given time, said control computeroperatively connected:

to said first generating means station for receiving the address codesrepresenting the destination of said articles from said first generatingmeans station, to said depositing means for controlling the deposit ofsaid articles of like address codes in the same ones of said slots, tosaid first discharge means to control the release of said firstdischarge means for discharging said articles from said slots, to saidcollection means for controlling said collection means to accept saidarticles discharged from said slots by said first discharge means, tosaid tying means for controlling said tying means to selectively tiesaid articles in bundles and selectively pass the remainder of saidarticles into said collection stations, whereby articles deposited bysaid depositing means in one of a plurality of temporary holding sortingslots are discharged from said slot by said first discharge means underthe control of said control computer and is carried by said collectionmeans to a tying means where predetermined quantities of articles havingidentical codes are tied and diverted from the sorting machine.

2. The machine of claim 1 wherein said collecting means comprises anendless conveyor having compartments thereon, positioned to travelbeneath said slots 3. The machine of claim 2 wherein each of saidcompartments comprises:

means for retaining articles contained therein as said conveyor belttraverses an underside path; and

means for discharging from said compartments articles contained therein.

1. A machine for sorting articles by collecting them from randomly positioned locations from at least one of a plurality of supply sources, each article being in a respective one of a plurality of destination categories comprising: first generating means station for generating an address code representing the address of each of said articles; a primary sort means comprising a plurality of temporary holding slOts; depositing means for depositing each article in selected respective one of said slots; first discharge means for discharging from said slots the articles contained therein; collecting means for collecting and labeling the articles discharged by said first discharge means; tying means for selectively tying said articles collected by said collecting means; collection stations for storage of those of said articles not selectively tied by said tying means; a control computer, said control computer further comprising: a means for keeping a first running inventory of the number of articles in each address code by slot location and a first running count of the extent to which said plurality of sorting slots is occupied, a second generating means for generating a destination sort code, said destination sort code capable of activating through said computer, said first discharge means to discharge from said plurality of sorting slots all articles of a given destination category, in response to said means for keeping a first running inventory and said first running count said destination sort code being generated when less than an arbitrarily designated number of said plurality of sorting slots is occupied, third generating means for generating a dispatch sort code, said dispatch sort code capable of activating through the computer said first discharge means to discharge from said plurality of sorting slots articles of different destination categories, in response to said means for keeping a first running inventory and first running count, said dispatch sort code being generated when more than an arbitrarily designated number of said plurality of sorting slots is occupied, and first control and switching means responsive to said means for keeping a first running count and said arbitrarily designated number of said plurality of sorting slots filled at a given time, said control computer operatively connected: to said first generating means station for receiving the address codes representing the destination of said articles from said first generating means station, to said depositing means for controlling the deposit of said articles of like address codes in the same ones of said slots, to said first discharge means to control the release of said first discharge means for discharging said articles from said slots, to said collection means for controlling said collection means to accept said articles discharged from said slots by said first discharge means, to said tying means for controlling said tying means to selectively tie said articles in bundles and selectively pass the remainder of said articles into said collection stations, whereby articles deposited by said depositing means in one of a plurality of temporary holding sorting slots are discharged from said slot by said first discharge means under the control of said control computer and is carried by said collection means to a tying means where predetermined quantities of articles having identical codes are tied and diverted from the sorting machine.
 2. The machine of claim 1 wherein said collecting means comprises an endless conveyor having compartments thereon, positioned to travel beneath said slots.
 3. The machine of claim 2 wherein each of said compartments comprises: means for retaining articles contained therein as said conveyor belt traverses an underside path; and means for discharging from said compartments articles contained therein. 